1. Field of the Invention
The present invention relates to a solid-state imaging device using an imaging element, an imaging unit, and an imaging apparatus.
2. Description of the Related Art
Some of known imaging apparatuses have a Z-cut quartz plate formed of a single crystal containing small amounts of impurities such as heavy metals, the Z-cut quartz plate serving as a solid-state imaging element cover that seals the package (see Japanese Patent Laid-Open No. 2008-042797). Z-cut quartz plate is a quartz plate cut so that the normal to the major surfaces of the quartz plate is at a zero degree angle to the Z-axis, the optical axis of the quartz.
In the above-described known imaging apparatuses, at the time of reflow soldering in the mounting process or use of a camera in a high-temperature environment, the cover member glued to the package base deforms significantly, and there is a possibility that the cover member will peel or break. With the increase in deformation of the cover member, the width of separation of a ray of light obliquely incident on the quartz plate from the lens due to the double refraction property of the quartz plate increases. Because Z-cut quartz plate is a quartz plate cut perpendicularly to the Z-axis direction, ray separation occurs in directions corresponding to all of the vibration directions of incident light. As a result, the resolution of shot images decreases.